Well-Balanced Diet
Eating properly during pregnancy means having well-balanced meals. Your partner should be averaging an extra 300 calories a day during pregnancy. She should also be getting enough protein, fruits, and vegetables without adding extra fat and refined sugars to her diet. Calcium, folic acid, and other vitamins and minerals are also very important. 

Vegetarian Diet
If your partner is a vegetarian, she can continue to avoid meat during pregnancy without harming the baby. However, she needs to be more careful about getting enough protein and essential amino acids. If she doesn’t eat animal products such as milk and cheese, she may have a problem getting enough calcium, iron, riboflavin, vitamin B₁₂, vitamin D and zinc. Consulting a nutritionist would be a very good idea. 

If your partner is diabetic, her diet and glucose levels during the pregnancy need to be closely monitored by her doctor. Changes in medications and insulin can usually keep things under control.

Prenatal Vitamins
If your partner’s diet is well balanced, she should be getting an adequate amount of the important vitamins. However, because prenatal vitamins can offer many benefits without much risk, they are strongly recommended. The vitamins that doctors are particularly interested in supplementing are folic acid, calcium and iron.

Folic Acid
Folic acid has been shown to reduce the incidence of birth defects of the brain and spinal cord. Although many foods are fortified with folic acid, there is no obvious downside to taking an additional 0.4 mg of folate per day. 

Calcium
The average pregnant woman needs about 1200 mg of calcium every day to help the baby grow without affecting her bones in the process. Many women get much less than that. Because most prenatal vitamins contain only 200 - 300 mg of calcium, your partner should eat calcium-rich foods such as milk, cheese and yogurt, or she will probably need to take an additional calcium supplement. 

Iron
Both the baby and the mother need extra iron to make enough red blood cells. A low level of red blood cells is called anemia. Most prenatal vitamins contain at least 30 mg of iron, which is usually enough to prevent anemia. However, it is not uncommon for a woman to be iron deficient at the start of a pregnancy due to previous menstrual bleeding, or to become anemic during the pregnancy. If she is or becomes anemic and has low iron levels, she will have to take a separate iron supplement. To help prevent this, she can eat food high in iron, including chicken, red meat, fish and leafy green vegetables, along with enriched breads and cereals. 

Vitamin C
Some people believe that vitamin C may help reduce the risk of a type of blood pressure disorder called preeclampsia. Whether that is accurate or not, getting a little extra vitamin C probably isn’t going to hurt; extra or unused vitamin C is usually eliminated quickly by the kidneys. 

Food Safety
Many people find it easier to focus on avoiding certain foods or food additives rather than concentrate on eating nutritious and appropriately sized meals. Your partner is going to read or hear about certain foods that may be dangerous during pregnancy, and she will probably try to avoid them. However, the research data supporting the danger isn’t as strong as many people make it out to be. Yet since it is safer to use a “why take a chance” approach, you and your partner should use your best judgment.